Finder for single lens reflex cameras including means to view associated camera structure



United States Patent Inventors Takeo Yamada Tokyo, Japan; Jun Shimomura,Tokyo, Japan Appl. No. 618,808 Filed Feb. 27, I967 Patented Aug. 18,1970 Assignee Nippon Kogaku K.K.

Tokyo, Japan a Corp. ofJapan FINDER FOR SINGLE LENS REFLEX CAMERASINCLUDING MEANS TO VIEW ASSOCIATED CAMERA STRUCTURE I Claim, 9 DrawingFigs.

US. Cl 88/15 ....G03b l3/I8 Field of Search 88/1 .5; 95/42, 44

[56] References Cited UNITED STATES PATENTS 3.174316 3/1965 Heerklotz88/].5X 3.250,l96 5/l966 Ortetal 88/LSUX 3,326,I04 6/l967 Mische88/l.5(W)UX Prinulry Examiner- Ronald L. Wihert Assistant Examiner-Orville B. Chew, ll Atmrnvy- Anton J. Wille ABSTRACT: A viewfinder for asingle lens reflex camera in which an image of the exposure meterpointer, stop values or distance scales on the lens barrel, or exposurefactors may he observed, the images being projected into the lowerportion of the visual field. A reflecting surface is provided betweenthe penta prism and the eyepiece of the view-finder below the ocularaxis, the image rays being directed through the penta prism onto thereflecting surface and reflected upwardly into the lower portion oftheviewfinderv Patented Au 18, 1-970 3,524,380

FIG. FIG. 3A F l%cqk\ Z r 75 UPPER 9 LOWER A 6 F FIG. 3B NOSE SIDE ETEMPLE SIDE VIEW OF RIGHT EYE (9 FIG- I D'J EE\D' v F I 1 F16. 3C jFINDER FOR SINGLE LENS REFLEX CAMERAS INCLUDING MEANS TO VIEW ASSOCIATEDCAMERA STRUCTURE This invention relates to a view-finder for single lensreflex cameras.

In accordance with the present invention, a view-finder is provided fora single lens reflex camera wherein a penta-dach prism is used inconjunction with a reflecting surface, the reflecting surface beingdisposed between the prism and an eye-piece lens to reflect the imagerays which pass through the front non-reflecting surface of the prismfrom the exposure meter indicator, and the like, onto the lower orlower, outer portion of the visual field of the view-finder.

Single lens reflex cameras having view-finders wherein the pointer of anexposure meter, stop values, or similar exposure factors, or distancescales can be observed, are already known. Such exposure guides aregenerally over-lapped on the field of view of the finder, or placed onthe upper outside portion or on one side of the field view.

The object of the present invention is to place the images of suchexposure factors, or the like, on the lower or lower, outside portion ofthe field of view of the view-finder more in keeping with a humanengineering point of view respecting eye responsiveness and acuity.

Other objects, advantages and features of the present invention will bemore clearly understood referring to the following description inconjunction with illustrative embodiments of the invention shown in thedrawing, in which:

FIG. I shows a chart of the responsiveness of the human eye over theentire 360 field of view;

FIGS. 2A, 2B and 2C, respectively show schematically, variousembodiments of the present invention;

FIGS. 3A, 3B and 3C, respectively show the visual fields observed in theembodiments illustrated in FIGS. 2A, 2B, and 3C; and

FIGS. 4A and 48, respectively show schematically another embodiment ofthe present invention.

FIG. I shows the responsiveness of the human eye over the entire fieldof view, in which E represents the central position of the eye and 2shows the border or edge of the visual field. As viewed from thestandpoint of human engineering the visual field ofa human eye is widerin the lower portion than in the upper portion as apparent from FIG. I,the greater lobe being in the lower, outer portion. It is known thatless fatigue is felt and it is easier to observe objects which are inthe lower portion of the field of view and preferably when such objectsare in the lower, outer portion of the visual field.

With this consideration of the responsiveness of the human eye, andreferring now to FIG. 2A of the drawings, the object D, which may be anexposure factor, or the like, is engraved on the camera lens barrel,mounting rings, etc. (not shown). A penta dach prism I is providedhaving a non-reflecting surface 2 and cooperates with an eyepiece 3.Disposed between the prism 1 and the eyepiece 3 and below the opticalaxis of the prism and eyepiece, is a reflective surface member 4.Cooperating with the prism surface 2 is another prism 5, which, togetherwith an auxiliary lens 6, and a reflecting surface 7, reflects the imagerays of the object D, as for example arrow 8 in FIG. 2A, through theprism 1 onto reflective member 4 and through the eyepiece into the lowerportion of the field of view to provide an image D as shown in FIG. 3A.

FIG. 2B shows an embodiment wherein the object D such as a scaleinterlocked to the exposure factors, is provided within a camera body,and the light penetrating portion 2a is provided on a portion of thenon-reflecting surface 2. The object D is directly observed, and theauxiliary lens 6, compensating for the length of light path, isconnected to the lower portion of eye-piece lens 3. The observed image Din the visual field is shown in FIG. 38.

FIG. 2C is another embodiment wherein it is possible to observe theobject D from the upper portion of a camera as well as from the backside of the camera as in the case of an exposure meter pointer providedon the upper portion of the camera body. In this embodiment, theimageD'of the object D is normal, and the position thereof being formedat the lower portion of the visual field of the finder as is shown inFIG. 3C.

The auxiliary lens 6, compensating for the length of light path, is usedfor adjusting the degree of distinctiveness of the images of the twooptional systems, i.e., the optical system for the view-finder and theoptical system for observing the object, when there is a largedifference between the lengths of light paths of the two opticalsystems. lt is not always necessary to use an auxiliary lens asillustrated, the reflecting surface of member 4 or 5 may be a concave orconvex mirror, respectively, as shown in FIG. 4A or 4B, and achieve thesame results.

In accordance with the present invention as described above, theview-finder provided thereby is such that the scales or indicators areobserved at the lower portion of the view frame of the finder inconformity with the responsiveness of the human eye without shielding orover-lapping of images in the finder view. The view-finder arrangementof the present invention is such that it is not necessary to increasethe size of the penta dach prism for this purpose, thus providing a verycompact and simple arrangement without adding to the camera,particularly in the vicinity of the camera lens, another optical systemto provide the exposure factor images in the view-finder as in the priorart.

We claim:

1. ln a view-finder for a single lens reflex camera having a penta prismand an eye lens, the combination comprising:

a reflecting surface member disposed between the prism and the eye lens,the reflecting surface of said member being below and approximatelyparallel with the light ray path of the finder view field along theoptical axis of the eye lens,

a transparent portion of a non-reflecting front surface of the pentaprism provided above the optical axis of the eye lens,

and means adjacent said transparent portion for directing the light raysfrom an object through said transparent portion and through the pentaprism onto the surface of said reflecting surface member for reflectingthe light rays into the lower portion of the field view of the eye lens,the light my path of the object obliquely crossing the optical axis ofthe eye lens in the penta prism.

